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* [gcc r14-8170] libstdc++: Implement P2540R1 change to views::cartesian_product()
@ 2024-01-17 2:21 Patrick Palka
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From: Patrick Palka @ 2024-01-17 2:21 UTC (permalink / raw)
To: gcc-cvs, libstdc++-cvs
https://gcc.gnu.org/g:98966f32f906303cd7d2e1c418f320c483e6dcbe
commit r14-8170-g98966f32f906303cd7d2e1c418f320c483e6dcbe
Author: Patrick Palka <ppalka@redhat.com>
Date: Tue Jan 16 21:20:12 2024 -0500
libstdc++: Implement P2540R1 change to views::cartesian_product()
This paper changes the identity element of views::cartesian_product to a
singleton range instead of an empty range. It was approved alongside
the main cartesian_product paper P2374R4, but unfortunately was overlooked
when implementing the main paper.
libstdc++-v3/ChangeLog:
* include/std/ranges (views::_CartesianProduct::operator()):
Adjust identity case as per P2540R1.
* testsuite/std/ranges/cartesian_product/1.cc (test01):
Adjust expected result of the identity case.
Reviewed-by: Jonathan Wakely <jwakely@redhat.com>
Diff:
---
libstdc++-v3/include/std/ranges | 2 +-
libstdc++-v3/testsuite/std/ranges/cartesian_product/1.cc | 6 +++---
2 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
index 3135e6f0c08..7ef835f486a 100644
--- a/libstdc++-v3/include/std/ranges
+++ b/libstdc++-v3/include/std/ranges
@@ -8748,7 +8748,7 @@ namespace views::__adaptor
operator() [[nodiscard]] (_Ts&&... __ts) const
{
if constexpr (sizeof...(_Ts) == 0)
- return views::empty<tuple<>>;
+ return views::single(tuple{});
else
return cartesian_product_view<all_t<_Ts>...>(std::forward<_Ts>(__ts)...);
}
diff --git a/libstdc++-v3/testsuite/std/ranges/cartesian_product/1.cc b/libstdc++-v3/testsuite/std/ranges/cartesian_product/1.cc
index f69f965c0ce..7281cd8a2f4 100644
--- a/libstdc++-v3/testsuite/std/ranges/cartesian_product/1.cc
+++ b/libstdc++-v3/testsuite/std/ranges/cartesian_product/1.cc
@@ -24,9 +24,9 @@ test01()
int w[] = {9};
auto v0 = views::cartesian_product();
- VERIFY( ranges::end(v0) - ranges::begin(v0) == 0 );
- VERIFY( ranges::size(v0) == 0 );
- VERIFY( ranges::empty(v0) );
+ VERIFY( ranges::end(v0) - ranges::begin(v0) == 1 );
+ VERIFY( ranges::size(v0) == 1 );
+ VERIFY( !ranges::empty(v0) );
auto v1 = views::cartesian_product(x);
VERIFY( ranges::end(v1) - ranges::begin(v1) == 3 );
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